[clang] [HLSL][RootSignature] Add basic parameter validations of Root Elements (PR #145795)

[Aaron Ballman via cfe-commits]

================
@@ -1083,6 +1085,92 @@ void SemaHLSL::ActOnFinishRootSignatureDecl(
 
 bool SemaHLSL::handleRootSignatureElements(
     ArrayRef<hlsl::RootSignatureElement> Elements) {
+  // Define some common error handling functions
+  bool HadError = false;
+  auto ReportError = [this, &HadError](SourceLocation Loc, uint32_t LowerBound,
+                                       uint32_t UpperBound) {
+    HadError = true;
+    this->Diag(Loc, diag::err_hlsl_invalid_rootsig_value)
+        << LowerBound << UpperBound;
+  };
+
+  auto ReportFloatError = [this, &HadError](SourceLocation Loc,
+                                            float LowerBound,
+                                            float UpperBound) {
+    HadError = true;
+    this->Diag(Loc, diag::err_hlsl_invalid_rootsig_value)
+        << llvm::formatv("{0:f}", LowerBound).sstr<6>()
+        << llvm::formatv("{0:f}", UpperBound).sstr<6>();
+  };
+
+  auto VerifyRegister = [ReportError](SourceLocation Loc, uint32_t Register) {
+    if (!llvm::hlsl::rootsig::verifyRegisterValue(Register))
+      ReportError(Loc, 0, 0xfffffffe);
+  };
+
+  auto VerifySpace = [ReportError](SourceLocation Loc, uint32_t Space) {
+    if (!llvm::hlsl::rootsig::verifyRegisterSpace(Space))
+      ReportError(Loc, 0, 0xffffffef);
+  };
+
+  const uint32_t Version =
+      llvm::to_underlying(SemaRef.getLangOpts().HLSLRootSigVer);
+  const uint32_t VersionEnum = Version - 1;
+  auto ReportFlagError = [this, &HadError, VersionEnum](SourceLocation Loc) {
+    HadError = true;
+    this->Diag(Loc, diag::err_hlsl_invalid_rootsig_flag)
+        << /*version minor*/ VersionEnum;
+  };
+
+  // Iterate through the elements and do basic validations
+  for (const hlsl::RootSignatureElement &RootSigElem : Elements) {
+    SourceLocation Loc = RootSigElem.getLocation();
+    const llvm::hlsl::rootsig::RootElement &Elem = RootSigElem.getElement();
+    if (const auto *Descriptor =
+            std::get_if<llvm::hlsl::rootsig::RootDescriptor>(&Elem)) {
+      VerifyRegister(Loc, Descriptor->Reg.Number);
+      VerifySpace(Loc, Descriptor->Space);
+
+      if (!llvm::hlsl::rootsig::verifyRootDescriptorFlag(
+              Version, llvm::to_underlying(Descriptor->Flags)))
+        ReportFlagError(Loc);
+    } else if (const auto *Constants =
+                   std::get_if<llvm::hlsl::rootsig::RootConstants>(&Elem)) {
+      VerifyRegister(Loc, Constants->Reg.Number);
+      VerifySpace(Loc, Constants->Space);
+    } else if (const auto *Sampler =
+                   std::get_if<llvm::hlsl::rootsig::StaticSampler>(&Elem)) {
+      VerifyRegister(Loc, Sampler->Reg.Number);
+      VerifySpace(Loc, Sampler->Space);
+
+      assert(!std::isnan(Sampler->MaxLOD) && !std::isnan(Sampler->MinLOD) &&
+             "By construction, parseFloatParam can't produce a NaN from a "
+             "float_literal token");
+
+      if (!llvm::hlsl::rootsig::verifyMaxAnisotropy(Sampler->MaxAnisotropy))
+        ReportError(Loc, 0, 16);
+      if (!llvm::hlsl::rootsig::verifyMipLODBias(Sampler->MipLODBias))
+        ReportFloatError(Loc, -16.f, 15.99);
----------------
AaronBallman wrote:

Thank you! And no worries on timing, I'm not aware of any bots that are down because of this.

https://github.com/llvm/llvm-project/pull/145795